Transmit Procedures

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The CAN controller provides 32 transmit message holding buffers. An internal priority arbiter selects the message according to the chosen arbitration scheme. Upon transmission of a message or message arbitration loss, the priority arbiter re-evaluates the message priority of the next message. The following figure gives an overall view of the transmit message buffers.

Figure 1. Transmit Message Buffers

Two types of message priority arbitration are supported. The type of arbitration is selected using the CAN_CONFIG configuration register. Following are the arbitration types:

Note: RTR message requests are served before transmit message buffers are handled. For example, RTRreq0, RTRreq31, TxMessage0, TxMessage1, and TxMessage31.